Effects of dialyzable leukocyte extracts (DLE) and inosine on stimulated lymphocytes

The effects of dialyzable leukocyte extracts (DLE) on the lymphocytes were examined. The crude DLE suppressed the blast-formation of the PHA-stimulated lymphocytes and proliferation of the leukemic cell-lines but enhanced that of the fibroblastic cells. A certain fraction of the DLE caused the ATP level of the stimulated lymphocytes to rise, after incubation for 24 hours. The fraction was further purified and the inosine eluted from it. The inosine increased the ATP level and markedly enhanced the lymphocyte blast-formation and proliferation of the fibroblastic cells and leukemic cell-lines. It is suggested that when the DLE show some effects on the lymphocytes, the inosine contained in the DLE may show important effects. The effect of inosine was inhibited by other substances contained in the DLE, especially deoxynucleotides. These substances suppressed the blast-formation of the lymphocytes and the proliferation of the leukemic-cell lines. It remains to determine why the fibroblastic cells were not suppressed by them.